In the field of abrasive grinding, it is often considered desirable to gauge the degree of material removal during the grinding process to ensure that accurate grinding is taking place, and that only desired material is removed. To this end, apertures formed in the grinding media of rotating grinding elements have been employed to assist a user in making these determinations. The apertures make it possible to constantly monitor the grinding result during grinding. Furthermore, heating of the target workpiece is reduced by the apertures due to intrinsic cooling.
The prior art also recognizes the advantages of flapped grinding discs: those that have a plurality of grinding blades or flaps that are positioned in an overlapping relationship such as shingles. This configuration permits grinding operations to be carried out on contoured or irregular surfaces. Realizing the benefits of both flapped grinding disks and apertured disks, the prior art includes flapped grinding disks that use apertures. For example, a flapped grinding disk employing apertures is known from DE-U-202 14 389 wherein the apertures are segment-shaped, i.e. they are cut off from the periphery by a cut which is guided along a chord.
A similar flapped grinding disk is also known from U.S. Pat. No. 6,007,415, the aperture being able to have any form and segment-shaped apertures specifically again being described.
Flapped grinding disks with a circular periphery and without inspection apertures are known from DE-U-92 05 471, DE-A-40 31 454, DE-A-44 30 229 and WO99/16583.
Grinding and cutting-off disks in which granular abrasive is applied direct to the disk- or plate-shaped support and in which inspection apertures are provided are also known from DE-A-1 652 912, DE-U-298 02 791 and WO00/35634. The inspection apertures are circular openings in the support or cuts with rounded flanks provided at the periphery.
A grinding disk with a disk-shaped support and with grinding blades (flaps) that are fixed overlapping each other in the manner of scales or shingles on the support in an adhesive bed is publicly known. In this grinding disk, the apertures are approximately trapezoidal or have the form of part of a circular ring (annulus), where the edges of the apertures run approximately radially. In this referenced configuration, the aperture is defined on three sides by the grinding flaps.